The present invention relates to a method and apparatus in the production of metal can bodies.
The production of metal cans is a highly developed industrial field, with millions of metal cans being produced each day. The formation of the cylindrical part of a can, called the "can body", must be at a high rate of production and without waste of material, in order to be economical.
The prior issued patents have suggested that one method of producing can bodies is to form score lines crosswise on an elongated metal body plate. The plate is then joined along two sides to form an elongated tube. The score lines are completely around the circumference of the formed tube. In effect, each score line is a ring perpendicular to the imaginary axis of the tube. The tube portion between two adjacent score lines forms a can body. The tube is then conveyed between a set of rollers which turns the end can body at an angle to the axis of the elongated tube, causing the can bodies to part (separate) along each score line. That method, using a series of opposed rollers at different angles to an axis, is shown in U.S. Pat. No. 3,068,344 entitled "Combination Electrical and Mechanical Can Separating Means On Continuous Welding Machines" and U.S. Pat. No. 2,444,463 entitled "Method of Producing Can Bodies". In U.S. Pat. No. 3,257,055 entitled "Oscillating Breakoff Mechanism For Separating Scored Can Bodies", the can bodies along the elongated tube are separated by sets of rollers which oscillate relative to the imaginary axis of the tube.
The use of aligned score lines on opposite sides of a metal blank, which is then broken along the score line, is known from U.S. Pat. No. 3,821,911 entitled "Apparatus For Forming Opposed Score Lines Between Rows of Characters On One Or Both Sides Of A Thin Metal Plate". The score lines are formed by opposed circular blades and the blank is used to form a scored metal sheet, having letters or numerals, which may be broken off from the sheet. Similarly, in U.S. Pat. No. 2,053,375 entitled "Bar Making Process", opposed score-forming rollers form aligned upper and lower score lines in a metal bar which, in a subsequent step, is broken along the score line.